The long term durability of bond strengths to dentin

The aim of this study was to investigate the durability, throughout one year, of tensile bond strengths (TBS) to bovine dentin using various commercial and experimental bonding systems. Specimens were stored in a controlled solution of ion-exchanged water containing plaster chips and sodium azide. From the results it was concluded that the changes in TBS were not uniform over time, but a significant decrease was usually observed. For Super Bond D-liner and KB-100, the TBS were the highest and exhibited remarkable stability over the test period. The mode of fracture was noted to vary depending on the treatment system used, and was independent of TBS. Generally, the fracture mode tended to show increases in adhesive/cohesive failures within the resin over time. Super Bond D-liner always exhibited adhesive type failure at the tooth interface, and later involved failure in the hybrid layer. KB-100 showed very little change in failure over one year, being usually adhesive between bonding resin and resin composite. The results from this study indicate the need to carry out durability studies for the basic evaluation of all bonding systems. It was shown that the use of a controlled storage solution is important.